SharkCam

1. Several great white sharks have been sighted in Cape Cod waters in recent years. (Greg Skomal)

2. The growing number of shark sightings is likely linked to the rising population of seals, the meal-of-choice for great whites. Here, a grey seal displays a battle scar from a shark encounter. (Big Wave Production)

3. Local seals were once hunted down to near extinction, mostly because they competed with fishermen for fish. But the seal population has rebounded since they began to receive greater legal protection. An aerial view shows a grey seal population that has taken up residence on a sand spit near the town of Chatham, Mass. (Big Wave Productions)

4. While sharks are following seals, something else is now on the trail of the sharks. Amy Kukulya, an engineer at Woods Hole Oceanographic Institution, left, and Greg Skomal, a biologist at Massachusetts Marine Fisheries, teamed up with Big Wave Productions and Discovery Channel to create and test an experimental autonomous underwater vehicle that for the first time could track and film a live moving shark. (Big Wave Productions)

5. After initial testing, the team used an autonomous underwater vehicle called REMUS to trac their first live animal, Greg Skomal. REMUS followed Skomal, who rides a dive scooter with a tag attached. The bread-loaf sized tag, called a transponder, sends acoustic signals to REMUS. (Oceanographic Systems Laboratory, Woods Hole Oceanographic Institution)

6. Greg Skomal and Amy Kukulya celebrate after REMUS successfully kept on Skomal’s trail. REMUS and the team moved to the next phase: shark tracking. (Big Wave Productions)

7. Because sharks swimming beneath the surface are hard to spot, the team hired a spotter pilot to locate sharks from the air. (Greg Skomal)

8. When the spotter plane pilot located a shark, he alerted crew and researchers aboard the fishing vessel Ezyduzit. (Big Wave Productions)

13. The REMUS SharkCam is launched on a mission to follow close behind the shark by communicating with the transponder via sound “pings.” (Oceanographic Systems Laboratory, Woods Hole Oceanographic Institution)